B.M. Kovalchuk

High-power ultrawideband electromagnetic pulse radiation

Basing on energetic processes studying in the near-field radiator zone, a new concept of antenna synthesizing for ultrawideband electromagnetic pulse radiation has been suggested. The results of experimental investigations of the antennae developed with using of this concept for high-power applications are presented. The antennae have small dimensions, high electrical strength, cardioid pattern with linear polarization of the pulse radiated and they are ideally adapted to be used as a steering antenna array element. A high-voltage nanosecond bipolar pulse generator design to excite antennae is described.

A terawatt pulse-power generator with a microsecond plasma-opening switch

A review of the first experiments with the GIT-4 generator is given. GIT-4 is based on the results obtained previously on Gamma (1985) and Marina (1986) generators and has operated since December 1986. GIT-4 is designed to test the concept of a terawatt pulsed-power generator based on the direct charging of an inductive storage from a Marx primary store using a plasma-opening switch (POS) at currents up to several mega-amperes. Such generators need a POS with essentially microsecond conduction times. In the experiments reviewed, output powers up to 2.5 TW in the POS region were obtained at current levels up to 1 MA. >

High-power sources of ultra-wideband radiation with subnanosecond pulse lengths

Sources of high-power ultra-wideband electromagnetic pulses of nanosecond duration are described. A bipolar voltage pulse with a length of 0.5 ns and an amplitude of ∼200 kV is fed to the input of a radiating system (a 16-element array antenna or a single antenna). The values of the effective radiation potential EpR = 260 kV for a source with a single antenna and EpR = 690 kV for a source with a 16-element antenna array were obtained at a pulse repetition frequency of 100 Hz.

Microsecond Plasma Opening Switches

This review presents the results of experiments with plasma opening switches (POSs) in which energy delivery to the storage inductor occurs on a microsecond time scale. Under these conditions, the POS insures an impedance rate of rise of ~109 ¿/s to final values of ~10-20 ¿. These parameters allow the POS to be considered as a basis for the creation of unique ~ 1013-W pulsed power generators as well as compact ~1010-W commercial generators.

S-band vircator with electron beam premodulation based on compact pulse driver with inductive energy storage

This paper describes an S-band vircator system with electron beam premodulation, built on the base of the MARINA compact high-voltage pulser with inductive energy storage. The peak microwave output was /spl sim/1 GW with /spl sim/5% power efficiency and 50-ns full-width at half-maximum. The microwave frequency was constant during the pulse as determined by the resonator. Substantial spontaneous shortening of the microwave pulse was observed. Possible mechanisms for this phenomenon are discussed and supported by three-dimensional KARAT simulations.

Capacitor Bank Module for a Multimegajoule Energy Storage

Laser megajoule (LMJ) is a laser facility being built by the French nuclear science directorate, Commissariat a lEnergie Atomique. This facility is a large flashlamp pumped laser (1.8-MJ optical output). The pulsed power conditioning system of LMJ is based on a modular design of 480 modules (400-MJ energy capacitor bank). A new capacitor bank module (CBM) for the LMJ power conditioning system has been developed by the Institute of High Current Electronics (IHCE, Tomsk) in collaboration with International Technologies for High Pulsed Power (France). Two such modules were produced and tested in IHCE. The main parts of the CBM are the following: high-voltage power supplies, command control system, air conditioning system, capacitor block, and cables delivering the energy to a load. The parameters of the module are the following: total rated capacitance of 2900 (+4%) muF, charging voltage up to 24 kV, peak current amplitude of 240 kA, peak stored energy up to 864 kJ, pulsewidth at 10% of peak power of 360 mus, dimensions of 2.3 times 1.5 times 2.5 m3, and weight of ~2500 kg. In nominal regime (24-kV charging voltage, 40-m length cables), the energy delivered to flashlamps in each channel is 74 kJ (86% efficiency). No failures were observed in more than 1000 test shots, and all parameters of the CBM are well within the requirements. Detailed description of the module design, performance, and test results are stated in this paper.

A source of high-power pulses of elliptically polarized ultrawideband radiation.

Here, we describe a source of high-power ultrawideband radiation with elliptical polarization. The source consisting of a monopolar pulse generator, a bipolar pulse former, and a helical antenna placed into a radioparent container may be used in tests for electromagnetic compatibility. In the source, the helical antenna with the number of turns N = 4 is excited with a high-voltage bipolar pulse. Preliminary, we examined helical antennas at a low-voltage source aiming to select an optimal N and to estimate a radiation center position and boundary of a far-field zone. Finally, characteristics of the source in the operating mode at a pulse repetition rate of 100 Hz are presented in the paper as well. Energy efficiency of the antenna is 0.75 at the axial ratio equal to 1.3. The effective potential of radiation of the source at the voltage amplitudes of the bipolar pulse generator equal to -175/+200 kV reaches 280 kV.

MV multi channel closing switch for water storages

As a start point for the authors development in MV closing switches, the Sandia Rimfire switch was chosen that was successfully proved in different installations over a long period of time. This gas switch consists of a stack of intermediate electrodes that form a self breakdown section, connected in series with a trigger gap. The voltage across the self breakdown section relates to that of the trigger gap as /spl sim/3:1. The switch is triggered by closing the trigger gap resulting in overvoltage in the self breakdown section. After the gas gaps in this section break down the whole discharge current flows in multiple channels in self breakdown section and through the single spark in the trigger gap. In this paper, the authors present the design of several switch modifications and the results of the experiments on a testbed with 2.3 MV output voltage. On the given step of the work, the main goal was to prove the multi channel discharge along the whole length of the switch. The problems related to the switch body flashover were also considered but they will be the main goal of future work in this field.

High-power ultrawideband electromagnetic radiation generator

High-power ultrawideband electromagnetic pulse generator construction consisting of a bipolar pulse generator and a transmitting antenna is described. Electromagnetic pulse radiation characteristics when exciting a transmitting antenna by the pulses with the voltage U/spl plusmn/100 kV, duration /spl tau//spl ap/3.5 ns, and pulse rate 100 Hz are presented.

High-power ultrawideband electromagnetic pulse source

The source of high-power ultrawideband (UWB) radiation based on single compact antenna excited with 1-ns bipolar pulse has been created. Antenna input pulse amplitude is up to 120-kV and pulse repetition rate up to 100 Hz. The antenna efficiency by peak power was 60%. The peak power of the source was 170 MW. The antenna pattern width by half-power is 100/spl deg/ for the H-plane and 105/spl deg/ for the E-plane. The efficient voltage of the source equal to product of the peak field strength and the distance made /spl sim/130 kV.